In a process of unloading a tank container, when there is relatively few liquid remained in the container, unloading speed would be reduced, and unloading may not be completely carried out, moreover, the tank container mainly serves to transport hazardous chemicals, so that during unloading, a completely unloading must be guaranteed. Therefore, there is requirement to provide a lifting device at a frame longitudinal beam of a tank container transport vehicle (e.g., a trailer), in order to lift the front of the tank container to a determined height, thus increasing the unloading speed and assuring the unloading completely carried out.
At present, in domestic liquid tank transportation, it has been suggested to use a hydraulic oil cylinder as an assistant unloading device for a dump container semi-trailer. However, though the structure of such assistant unloading device has a strong lifting capability and a high lifting height, and is suitable for unloading viscous materials such as asphalt, it is too unwieldy, and puts forwarding relatively higher requirements for structural strength in installation.